Modular Power Converter

ABSTRACT

A power converter comprises an input connection to a single power source, an output connection to a single coil, and a daisy-chain connection coupled to the output connection and configured to enable coupling of at least one additional daisy-chained power converter and at least one respective additional power source to the single coil. The power converter further comprises a power integrator coupled between the input connection and the output connection and adapted for summing power from the power sources into a single voltage on the single coil and a time multiplexer coupled to the power integrator configured to control power integration.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to as a continuation-in-part and incorporates herein by reference in its entirety for all purposes, U.S. patent application Ser. No. 11/207,595 entitled “METHOD FOR HIGH VOLTAGE POWER FEED ON DIFFERENTIAL CABLE PAIRS,” by John R. Camagna, et al. filed Aug. 19, 2005; and No. 11/207,602 entitled “A METHOD FOR DYNAMIC INSERTION LOSS CONTROL FOR 10/100/1000 MHZ ETHERNET SIGNALLING,” by John R. Camagna, et al., which have been filed concurrently filed Aug. 19, 2005.

BACKGROUND

Many networks such as local and wide area networks (LAN/WAN) structures are used to carry and distribute data communication signals between devices. Various network elements include hubs, switches, routers, and bridges, peripheral devices, such as, but not limited to, printers, data servers, desktop personal computers (PCs), portable PCs and personal data assistants (PDAs) equipped with network interface cards. Devices that connect to the network structure use power to enable operation. Power of the devices may be supplied by either an internal or an external power supply such as batteries or an AC power via a connection to an electrical outlet.

Some network solutions can distribute power over the network in combination with data communications. Power distribution over a network consolidates power and data communications over a single network connection to reduce installation costs, ensures power to network elements in the event of a traditional power failure, and enables reduction in the number of power cables, AC to DC adapters, and/or AC power supplies which may create fire and physical hazards. Additionally, power distributed over a network such as an Ethernet network may function as an uninterruptible power supply (UPS) to components or devices that normally would be powered using a dedicated UPS.

Additionally, network appliances, for example voice-over-Internet-Protocol (VOIP) telephones and other devices, are increasingly deployed and consume power. When compared to traditional counterparts, network appliances use an additional power feed. One drawback of VOIP telephony is that in the event of a power failure the ability to contact emergency services via an independently powered telephone is removed. The ability to distribute power to network appliances or circuits enable network appliances such as a VOIP telephone to operate in a fashion similar to ordinary analog telephone networks currently in use.

Distribution of power over Ethernet (PoE) network connections is in part governed by the Institute of Electrical and Electronics Engineers (IEEE) Standard 802.3 and other relevant standards, standards that are incorporated herein by reference. However, power distribution schemes within a network environment typically employ cumbersome, real estate intensive, magnetic transformers. Additionally, power-over-Ethernet (PoE) specifications under the IEEE 802.3 standard are stringent and often limit allowable power.

IEEE 802.3af-2003 sets standards for powering devices over an Ethernet network including setting of a maximum power requirement to a powered device (PD). The standard does not address powering of powered devices that require power in excess of the specification.

SUMMARY

According to an embodiment of a network device, a power converter comprises an input connection to a single power source, an output connection to a single coil, and a daisy-chain connection coupled to the output connection and configured to enable coupling of at least one additional daisy-chained power converter and at least one respective additional power source to the single coil. The power converter further comprises a power integrator coupled between the input connection and the output connection and adapted for summing power from the power sources into a single voltage on the single coil and a time multiplexer coupled to the power integrator configured to control power integration.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention relating to both structure and method of operation may best be understood by referring to the following description and accompanying drawings:

FIGS. 1A and 1B are schematic block diagrams that respectively illustrate a high level example embodiments of client devices in which power is supplied separately to network attached client devices, and a switch that is a power supply equipment (PSE)-capable power-over Ethernet (PoE) enabled LAN switch that supplies both data and power signals to the client devices;

FIG. 2 is a functional block diagram illustrating a network interface including a network powered device (PD) interface and a network power supply equipment (PSE) interface, each implementing a non-magnetic transformer and choke circuitry;

FIGS. 3A and 3B are schematic block diagrams respectively illustrating examples of power controllers in isolated and non-isolated arrangements;

FIGS. 4A, 4B, 4C, and 4D are schematic block diagrams that depict embodiments of power converters that can integrate power from multiple sources into a single voltage;

FIG. 5 is a schematic block and circuit diagram depicting an embodiment of a power converter formed to control power source switching based on measured current;

FIGS. 6A and 6B are schematic block and circuit diagrams illustrating embodiments of Power-over-Ethemet (PoE) systems that implement power conversion to integrate power from multiple sources into a single voltage; and

FIG. 7A through 7D are flow charts illustrating embodiments of methods for power conversion in a network device.

DETAILED DESCRIPTION

A time multiplexed scheduling technique can be used to drive multiple converter circuits to integrate power from multiple sources into a single voltage, summing power from the multiple sources into a single flyback transformer or buck inductor.

In some applications, the technique can be used in Power-over-Ethernet implementations to integrate power from two sources in the case of four-pair arrangements.

In some embodiments, adaptive power sharing for the individual converters based on power availability of the associated source. When the current limit of a source is exceeded, the power from other sources can automatically feed power to suit requirements of the receiving device.

Power sources can be any suitable arrangement, for example a two-pair and an auxiliary power source.

The structure and technique may adaptively change current limits on each power source, enabling adaptive management of the amount of power that can be sourced from each power supply.

The structure and technique can be applied to enable both isolated and non-isolated power supply applications.

The structure and technique can also enable a user to develop a single-chip controller, for example a pulse width modulator (PWM) controller. As additional power sources become available, multiple single-chip controllers can be daisy-chained to schedule control while connecting output lines in parallel to a single flyback transformer or buck inductor.

Referring to FIGS. 3A and 3B, schematic block diagrams respectively illustrate examples of power controllers 300A, 300B in isolated and non-isolated arrangements. In either case, a pulse width modulator 312 is used to apply a power source 304 to a single coil 308. In FIG. 3A, the isolated power controller 300A is transformer-based whereby the single coil 308 is the primary winding of a transformer 324 and includes an opto-isolator 326 coupled to isolate a secondary winding of the transformer 324 from the power source 304. In FIG. 3B, the non-isolated power controller 300B has the single coil 308 in the form of a down or buck inductor.

In the illustrative implementation, the power controllers 300A, 300B are depicted as an integrated circuit 372 with components outside the integrated circuits 372 being external components.

The single integrated circuit 372 includes logic and timing elements which coordinate operations to drive the single coil 308 and internally to that IC the logic and the timing are set up for that single device.

The illustrative power controllers 300A, 300B apply a single power source 304 to the coil 308 and are limited in the amount of power that can be applied to the coil 308. What may be desired is a power controller that supports a connected device with a higher power requirement. Multiple power sources, for example multiple pairs of RJ-45 or Ethernet cables, or auxiliary power sources can be coupled to combine power, creating an integrated power relationship that combines into a single output power. Accordingly, circuits and systems are sought that enable combination of multiple supplies to support the higher power requirement.

One application that can greatly benefit from a capability to support a higher power level is a Power-over-Ethernet (PoE) application.

Referring to FIGS. 4A, 4B, 4C, and 4D, four schematic block diagrams depict embodiments of power converters 400 that can integrate power from multiple sources into a single voltage. The power converter 400A(1), 400B(1), 400C(1), 400D(1) has an input connection 402 to a single power source 404(1), an output connection 406 to a single coil 408, and a daisy-chain connection 410 coupled to the output connection 406 and configured to enable coupling of one or more additional daisy-chained power converters 400A(2), 400B(2), 400C(2), 400D(2) and one or more respective additional power sources 404(2) to the single coil 408. The power converter 400A(1), 400B(1), 400C(1), 400D(1) further comprises a power integrator 412 coupled between the input connection 402 and the output connection 406 that is adapted for summing power from the power sources 404(1), 404(2) into a single voltage on the single coil 408. A time multiplexer 414 is coupled to the power integrator 412 configured to control power integration.

The illustrative power converters 400A(1), 400B(1), 400C(1), 400D(1) can be implemented as single integrated circuit chips that can be used alone or can be used with two or more daisy-chained chips connected to combine multiple power sources.

Referring to FIG. 4A, the power converter 400A is configured as an isolated four-pair power integration structure. The power converter 400A comprises a pulse width modulation circuit 412 that functions as the power integrator. The illustrative time multiplexer 414 comprises an oscillator 416 and a divide-by-N circuit 418 whereby N corresponds to the number of daisy-chained power converters 400A. The time multiplexer 414A further can comprise a detect clock 420 which detects a clock signal from a daisy-chained power converter 400A. A multiplexer 422 receives input signals from the divide-by-N circuit 418 and the detect clock 420 and drives the pulse width modulation circuit 412.

In the isolated arrangement, the single coil 408 in the power converter 400A is a primary winding of a single flyback transformer 424. Optical isolators 426 isolate a secondary winding of the single flyback transformer 424.

In the depicted example arrangement, power converters 400A can be two integrated circuits that are identical or approximately identical and combine two power sources including a first source shown as Vpos1 and return Vrtn1, and a second source shown as Vpos2 and return Vret2. The first and second power sources can be sets of paired cables, such as Registered Jack (RJ)-45 connectors or Ethernet connectors, which connect two the two separate integrated circuits. The two separate integrated circuits are configured to energize the primary winding 408 of the flyback transformer 424 in a time multiplexed fashion.

The separate integrated circuits corresponding to the power converters 400A(1) and 400A(2) can be connected to a common output connection 406 to the single primary winding 408. Timing signal lines are connected, or daisy-chained, for each of the integrated circuits and are input to the detect clock 420, which in turn supplies a timing signal to the multiplexer 422. The timing signal from the other integrated circuit is applied to the detect clock 420 which generates a clock signal that is applied to the multiplexer 422. A divide-by-2 or more generically a divide-by-N 418 also generates a signal to the multiplexer 422 so that N power sources can be applied to the same primary winding 408. Accordingly, when a timing signal from another integrated circuit is asserted at the detect clock 420, then the other integrated circuit drives the primary 408, When the timing signal from the other integrated circuit is not asserted, the immediate integrated circuit drives the primary 408. For two power converter integrated circuits, each alternately drives the primary winding 408 in sequential time frames. For N power converter integrated circuits 400, each can drive the primary winding 408 for a portion of time in multiple time frames, for example in a round-robin fashion.

In various embodiments, the actual timing and framing can be arbitrary in a manner analogous to phasing. During one phase or time period the output signal to the coil 408 can be driven from one leg and then in another time period, another phase, another leg drives the output signal.

Time multiplexing facilitates power management by functioning as a control element for a feedback control system in which each power converter 400A(1) and 400A(2) has a feedback control loop. One power converter drives one feedback loop and the other power converter drives another feedback loop. Time multiplexing ensures that only one feedback loop is operational at any one time. For a system with N power converters, time multiplexing similarly ensures that only one of N feedback loops is operational at any time. The single power converter is operational in response to the respective associated feedback signal.

For the isolated power integration structure 400A, the common mode of the pairs can be completely different voltages, accordingly two opto-isolators 426 are used to ensure isolation.

Referring to FIG. 4B, the power converter 400B is configured as a non-isolated four-pair power integration structure. The power converter 400B comprises a pulse width modulation circuit 412 that functions as the power integrator. The illustrative time multiplexer 414B comprises an oscillator 416 and a divide-by-N circuit 418 whereby N corresponds to the number of daisy-chained power converters 400B. The time multiplexer 414B further can comprise a detect clock 420 which detects a clock signal from a daisy-chained power converter 400B. A multiplexer 422 receives input signals from the divide-by-N circuit 418 and the detect clock 420 and drives the pulse width modulation circuit 412.

In the non-isolated arrangement, the single coil 408 in the power converter 400A is a buck inductor 428.

For the non-isolated power converter 400B, a single feedback point can drive feedback loops for all power converters 400B(1), 400B(2), a suitable arrangement since the feedback loops are time multiplexed. Accordingly, the feedback is only active for one time period for one path and inactive for the other time period and the other path and vice versa.

Referring to FIG. 4C, the power converter 400C is configured as an isolated four-pair power integration structure. The power converter 400C comprises a pulse width modulation circuit 412 that functions as the power integrator. The illustrative time multiplexer 414C comprises a delay-locked loop 430 coupled to drive the pulse width modulation circuit 412, an oscillator 416, a detect clock 420 which detects a clock signal from a daisy-chained power converter 400C. A multiplexer 422 receives input signals from the oscillator 416 and the detect clock 420 and drives the delay-locked loop 430.

In the isolated arrangement, the single coil 408 in the power converter 400C is a primary winding of a single flyback transformer 424. Optical isolators 426 isolate a secondary winding of the single flyback transformer 424.

Referring to FIG. 4D, the power converter 400D is configured as a non-isolated four-pair power integration structure. The power converter 400D comprises a pulse width modulation circuit 412 that functions as the power integrator. The illustrative time multiplexer 414D comprises a delay-locked loop 430 coupled to drive the pulse width modulation circuit 412, an oscillator 416, a detect clock 420 which detects a clock signal from a daisy-chained power converter 400D. A multiplexer 422 receives input signals from the oscillator 416 and the detect clock 420 and drives the delay-locked loop 430.

In the non-isolated arrangement, the single coil 408 in the power converter 400D is a buck inductor 428.

In some embodiments, the power converters 400 can be implemented in a Power-over-Ethernet (PoE) integrated circuit with power sources 404 configured as two wire pairs coupled to a Registered Jack (RJ)-45 connector. The power converters 400 can further comprise a magnetic transformer, a Powered Device (PD) controller, a diode bridge that couples the power source 404 to the PD controller, and a Powered Device (PD) coupled to the single coil and powered by the single voltage.

In other similar embodiments, the power converters 400 can be implemented in a Power-over-Ethernet (PoE) integrated circuit with power sources 404 configured as two wire pairs coupled to a Registered Jack (RJ)-45 connector. The power converters 400 can further comprise a non-magnetic transformer and diode bridge integrated into the PoE integrated circuit and coupled to the RJ-45 connectors, a Powered Device (PD) controller, a diode bridge that couples the power source to the PD controller, and a Powered Device (PD) coupled to the single coil and powered by the single voltage.

In some embodiments, the time multiplexer 414 can be configured to perform adaptive power sharing for the power integrator 400 based on power availability of the single power source and the additional power sources.

The power sources 404 can be two-wire pair sources, as shown, or auxiliary sources such as home or office supply lines.

In some embodiments, the power converter 400 can implement adaptive power management by using IEEE 802.3at standard classification or similar classification techniques. For example, a Powered Device (PD) can be coupled to the single coil 408, powered by the single voltage, and one or more of the power sources 404 can be a Power Sourcing Equipment (PSE). A controller or other suitable logic can be configured to communicate detection, classification, and operational information between the Power Sourcing Equipment (PSE) and the Powered Device (PD) for accommodating a power consumption classification of the PD and identifying characteristics of the power sources, for example the amount of power supplied and type of power source. The identified power characteristics can be used for adaptive sharing power through management of the time multiplexer 414.

In a typical Ethernet IEEE 802.3af standard implementation, detection and classification signals are communicated from the PD to the PSE including a power-consumption classification. The PSE returns operational information, enabling a PD response to the classification voltage. Communication of information that identifies characteristics of the various power sources enables management of the time multiplexer 414 to account for differences in supplies.

Typically upon request from the PSE, the PD sends power-consumption classification information to the PSE that identifies the current power consumption demand of the PD, accounting for dynamic changes in demand. For example, the PD can be a scanning video camera that has relatively low steady state power consumption when scanning motors are not operating but may have a large power demand at possibly brief and infrequent operating times when the scanning motors are active.

The controller or logic can communicate detection, classification, and operational information independently for each power source of the single power source and the additional power sources and for current power consumption demand of the Powered Device (PD) for identifying characteristics of the power sources.

In some implementations, the power converter 400 can operate in a single integrated circuit chip configuration whereby a single power source 404 supplies the output connection to the single coil 408. In other implementations, the same power converter 400 can be connected to operate in combination with multiple single integrated circuit chip power converters 400 in a daisy chain configuration as additional power sources 404 become available. In the daisy chain configuration, time multiplexers 414 for the multiple power converters 400 schedule power source control with the output connections 406 coupled in parallel to the single coil 408.

The power converters 400C, 400D depicted in FIGS. 4C and 4D are operationally similar to power converters 400A, 400B shown in FIGS. 4A and 4B but illustrate a different structure and technique for generating the timing signals by usage of a delay-locked loop to generate the time periods. The delay-locked loop structure may be more useful in structures that include a number N, typically larger than 2, of integrated circuits that are staged one after another. The delay-locked loops are used to create the additional time periods. Like the divide-by-N implementation, the delay-locked loop circuit includes a clock detection but is driven differently. Each clock is driven from the output of the delay-locked loop and connected down a sequential chain.

Referring to FIG. 5, a schematic block and circuit diagram depicts an embodiment of a power converter 500 formed to control power source switching based on measured current. The power converter 500, in addition to a power integrator 512 and time multiplexer 514, further comprises a current sensor 570 coupled to the power integrator 512. The time multiplexer 514 can be configured to detect a current sensed by the current sensor 570 that exceeds a predetermined maximum current. In response to a current that exceeds the maximum current, the time multiplexer 514 switches power sourcing from the power source 504(1) at the input connection 502 to one of the additional power sources 504(2).

In some embodiments, the time multiplexer 514 can be configured to adaptively change the predetermined maximum current whereby power sourced by the single power source 504(1) and the additional power sources 504(2) is adaptively managed.

The various power converter arrangements can be used for any suitable power application. One example of a highly suitable application for usage of the power converters and the illustrative power conversion technique is a Power-over-Ethernet application. The combined power sources can be any suitable power source from various types of lines that are capable of supplying power including twisted pairs and Ethernet cables, as well as other power supply lines. In various applications, all power sources may be supplied on the same type of lines, or power sources may be connected from different types of lines.

The power sources can be supplied from communication lines, or may be a battery, a wall power source, or others.

Referring to FIGS. 6A and 6B, schematic block and circuit diagrams illustrate embodiments of a Power-over-Ethernet (PoE) system 650A, 650B that implement power conversion to integrate power from multiple sources into a single voltage. The Power-over-Ethernet (PoE) system 650A, 650B comprises one or more modular power converters 600(1), 600(2) configured for coupling between respective power sources 604(1), 604(2) and a single coil 608 of a Powered Device (PD) 652 in a daisy-chain arrangement whereby output connections 606 of the modular power converters 600(1), 600(2) are coupled in parallel to the single coil 608. The modular power converters 600(1), 600(2) can each comprise a power integrator 612 and a time multiplexed scheduler 614 that drives multiple power integrators 612 for multiple modular power converters 600 to integrate power from corresponding multiple sources 604 into a single voltage on the single coil 608.

As shown in FIG. 6A, the modular power converters 600A(1), 600A(2) can be implemented as a Power-over-Ethemet (PoE) integrated circuit. The power sources 604(1), 604(2) can be configured as two wire pairs coupled to a Registered Jack (RJ)-45 connector. The modular power converters 600A(1), 600A(2) can further comprise a magnetic transformer 654 coupled to the RJ-45 connector, a Powered Device (PD) controller 656 coupled to the power source 604(1), and a diode bridge 658 that couples the power source 604(1) to the PD controller 656.

In some embodiments, the time multiplexed scheduler 614 can be configured to perform adaptive power sharing for the power integrator 612 based on power availability of the power sources 604(1), 604(2).

In various applications and arrangements, the power sources 604(1), 604(2) can be two-wire pair sources, auxiliary sources, or the like.

As shown in FIG. 6B, the modular power converters 600B(1), 600B(2) can be implemented as a Power-over-Ethernet (PoE) integrated circuit. The power sources 604(1), 604(2) can be configured as two wire pairs coupled to Registered Jack (RJ)-45 connectors. The modular power converters 600B(1), 600B(2) can further comprise a non-magnetic transformer and diode bridge 660 integrated into the PoE integrated circuit and coupled to the RJ-45 connectors, a Powered Device (PD) controller 656 coupled to the power source 604(1) and coupled to the non-magnetic transformer and diode bridge 660. The modular power converters 600B(1), 600B(2) couple the power source 604(1) to the PD controller 656.

The non-magnetic transformer and diode bridge 660 can be a T-Less Connect™ solid-state transformer that separates Ethernet signals from power signals and/or that operates by floating ground potential of the Ethernet PHY relative to earth ground.

Various embodiments of Power-over-Ethernet (PoE) systems can be formed in various configurations. For example, the single coil 608 can be a primary winding of a single flyback transformer or a buck inductor. In various implementations, the power integrator 612 can be a Pulse Width Modulator (PWM), a forward bridge, a half bridge, a Pulse Frequency Modulator (PFM), a Pulse Amplitude Modulator (PAM), or any other suitable conversion device or technique. The time multiplexed scheduler 614 can be implemented based on any suitable control element such as a divide-by-N circuit, a Delay-Locked Loop (DLL), or similar devices.

The power converter 600 can further by constructed to adaptively control the power integrator 612 according to the IEEE 802.3at standard or similar classification techniques. The Powered Device (PD) 652 can communication with power sources 604 that may include a Power Sourcing Equipment (PSE). The PD controller 656 may include a processor, controller, or other logic, or another logic in the power converter 600 can be used to communicate detection, classification, and operational information between the Power Sourcing Equipment (PSE) and the Powered Device (PD) 652, enabling identification of characteristics of the associated power source so that the time multiplexed scheduler 614 can adaptively share power.

In various PoE system embodiments, the modular power converters can further comprise a current sensor coupled to the power integrator in combination with a the time multiplexed scheduler configured to detect a current sensed by the current sensor that exceeds a predetermined maximum current. In response to a current exceeding the maximum current, the time multiplexed scheduler can switch sourcing of the power sources.

In further embodiments, the time multiplexed scheduler can be configured to adaptively change the predetermined maximum current so that power sourced by the power sources is adaptively managed.

In the illustrative embodiments, each modular power converter 600B(1) and 600B(2) has two-pair input connections. Each two-pair connection passes through a diode bridge 660. As a result, a particular power is delivered through each power converter integrated circuit and a load shares the power supplied between the two converters. Power is summed from each of the two groups of pairs. The modular power converters not only route the power but also sum the power. For purposes of example only, ten watts may be supplied by one power source and ten by the second power source so that a total of twenty watts can be generated at the coil. Note that any suitable wattage may be summed for any suitable number of daisy-chained converters. Note also that the power sourced by the individual sources can be different.

Referring to FIG. 7A with reference to FIGS. 6A and 6B, a flow chart illustrates an embodiment of a method 700 for power conversion in a network device. Power is integrated 702 from multiple sources into a single voltage with power integration driven 706 according to time multiplexed scheduling 704. The integrated power is applied 708 onto a single winding of a flyback transformer or buck inductor.

Referring to FIG. 7B also with reference to FIGS. 6A and 6B, a flow chart illustrates an embodiment of a method 710 in which power is converted 712 for usage in an application of a Power-over-Ethernet (PoE) configuration. Power is integrated 714 from at least two sources selected from two-wire pair sources and auxiliary sources.

Referring to FIG. 7C, a flow chart depicts an embodiment of a method 720 that adaptively controls power. The method further comprises determining 722 power available among the multiple sources and adaptively sharing 724 power based on availability from the different sources.

Some embodiments may use additional measured parameters to adaptively control power sourcing. For example, FIG. 7D illustrates an embodiment of a power control method 730 that can be implemented in combination with the structures shown in FIG. 5. The method 730 may further comprise measuring 732 current associated with the power sources and determining 734 when the measured current exceeds a predetermined current limit. Power sourcing can be adaptively switched 736 when the current limit is exceeded. In some embodiments, current limits for the power sources can be adaptively changed 738, enabling adaptive management 740 of the power sourced among the power sources.

The IEEE 802.3 Ethernet Standard, which is incorporated herein by reference, addresses loop powering of remote Ethernet devices (802.3af). Power over Ethernet (PoE) standard and other similar standards support standardization of power delivery over Ethernet network cables to power remote client devices through the network connection. The side of link that supplies power is called Powered Supply Equipment (PSE). The side of link that receives power is the Powered device (PD). Other implementations may supply power to network attached devices over alternative networks such as, for example, Home Phoneline Networking alliance (HomePNA) local area networks and other similar networks. HomePNA uses existing telephone wires to share a single network connection within a home or building. In other examples, devices may support communication of network data signals over power lines.

In various configurations described herein, a magnetic transformer of conventional systems may be eliminated while transformer functionality is maintained. Techniques enabling replacement of the transformer may be implemented in the form of integrated circuits (ICs) or discrete components.

FIG. 1A is a schematic block diagram that illustrates a high level example embodiment of devices in which power is supplied separately to network attached client devices 112 through 116 that may benefit from receiving power and data via the network connection. The devices are serviced by a local area network (LAN) switch 110 for data. Individual client devices 112 through 116 have separate power connections 118 to electrical outlets 120. FIG. 1B is a schematic block diagram that depicts a high level example embodiment of devices wherein a switch 110 is a power supply equipment (PSE)-capable power-over Ethernet (PoE) enabled LAN switch that supplies both data and power signals to client devices 112 through 116. Network attached devices may include a Voice Over Internet Protocol (VOIP) telephone 112, access points, routers, gateways 114 and/or security cameras 116, as well as other known network appliances. Network supplied power enables client devices 112 through 116 to eliminate power connections 118 to electrical outlets 120 as shown in FIG. 1A. Eliminating the second connection enables the network attached device to have greater reliability when attached to the network with reduced cost and facilitated deployment.

Although the description herein may focus and describe a system and method for coupling high bandwidth data signals and power distribution between the integrated circuit and cable that uses transformer-less ICs with particular detail to the IEEE 802.3af Ethernet standard, the concepts may be applied in non-Ethernet applications and non-IEEE 802.3af applications. Also, the concepts may be applied in subsequent standards that supersede or complement the IEEE 802.3af standard.

Various embodiments of the depicted system may support solid state, and thus non-magnetic, transformer circuits operable to couple high bandwidth data signals and power signals with new mixed-signal IC technology, enabling elimination of cumbersome, real-estate intensive magnetic-based transformers.

Typical conventional communication systems use transformers to perform common mode signal blocking, 1500 volt isolation, and AC coupling of a differential signature as well as residual lightning or electromagnetic shock protection. The functions are replaced by a solid state or other similar circuits in accordance with embodiments of circuits and systems described herein whereby the circuit may couple directly to the line and provide high differential impedance and low common mode impedance. High differential impedance enables separation of the physical layer (PHY) signal from the power signal. Low common mode impedance enables elimination of a choke, allowing power to be tapped from the line. The local ground plane may float to eliminate a requirement for 1500 volt isolation. Additionally, through a combination of circuit techniques and lightning protection circuitry, voltage spike or lightning protection can be supplied to the network attached device, eliminating another function performed by transformers in traditional systems or arrangements. The disclosed technology may be applied anywhere transformers are used and is not limited to Ethernet applications.

Specific embodiments of the circuits and systems disclosed herein may be applied to various powered network attached devices or Ethernet network appliances. Such appliances include, but are not limited to VoIP telephones, routers, printers, and other similar devices.

Referring to FIG. 2, a functional block diagram depicts an embodiment of a network device 200 including a T-Less Connect™ solid-state transformer. The illustrative network device comprises a power potential rectifier 202 adapted to conductively couple a network connector 232 to an integrated circuit 270, 272 that rectifies and passes a power signal and data signal received from the network connector 232. The power potential rectifier 202 regulates a received power and/or data signal to ensure proper signal polarity is applied to the integrated circuit 270, 272.

The network device 200 is shown with the power sourcing switch 270 sourcing power through lines 1 and 2 of the network connector 232 in combination with lines 3 and 6.

In some embodiments, the power potential rectifier 202 is configured to couple directly to lines of the network connector 232 and regulate the power signal whereby the power potential rectifier 202 passes the data signal with substantially no degradation.

In some configuration embodiments, the network connector 232 receives multiple twisted pair conductors 204, for example twisted 22-26 gauge wire. Any one of a subset of the twisted pair conductors 204 can forward bias to deliver current and the power potential rectifier 202 can forward bias a return current path via a remaining conductor of the subset.

FIG. 2 illustrates the network interface 200 including a network powered device (PD) interface and a network power supply equipment (PSE) interface, each implementing a non-magnetic transformer and choke circuitry. A powered end station 272 is a network interface that includes a network connector 232, non-magnetic transformer and choke power feed circuitry 262, a network physical layer 236, and a power converter 238. Functionality of a magnetic transformer is replaced by circuitry 262. In the context of an Ethernet network interface, network connector 232 may be a RJ45 connector that is operable to receive multiple twisted wire pairs. Protection and conditioning circuitry may be located between network connector 232 and non-magnetic transformer and choke power feed circuitry 262 to attain surge protection in the form of voltage spike protection, lighting protection, external shock protection or other similar active functions. Conditioning circuitry may be a diode bridge or other rectifying component or device. A bridge or rectifier may couple to individual conductive lines 1-8 contained within the RJ45 connector. The circuits may be discrete components or an integrated circuit within non-magnetic transformer and choke power feed circuitry 262.

In an Ethernet application, the IEEE 802.3af standard (PoE standard) enables delivery of power over Ethernet cables to remotely power devices. The portion of the connection that receives the power may be referred to as the powered device (PD). The side of the link that supplies power is called the power sourcing equipment (PSE).

In the powered end station 272, conductors 1 through 8 of the network connector 232 couple to non-magnetic transformer and choke power feed circuitry 262. Non-magnetic transformer and choke power feed circuitry 262 may use the power feed circuit and separate the data signal portion from the power signal portion. The data signal portion may then be passed to the network physical layer (PHY) 236 while the power signal passes to power converter 238.

If the powered end station 272 is used to couple the network attached device or PD to an Ethernet network, network physical layer 236 may be operable to implement the 10 Mbps, 100 Mbps, and/or 1 Gbps physical layer functions as well as other Ethernet data protocols that may arise. The Ethernet PHY 236 may additionally couple to an Ethernet media access controller (MAC). The Ethernet PHY 236 and Ethernet MAC when coupled are operable to implement the hardware layers of an Ethernet protocol stack. The architecture may also be applied to other networks. If a power signal is not received but a traditional, non-power Ethernet signal is received the nonmagnetic power feed circuitry 262 still passes the data signal to the network PHY.

The power signal separated from the network signal within non-magnetic transformer and choke power feed circuit 262 by the power feed circuit is supplied to power converter 238. Typically the power signal received does not exceed 57 volts SELV (Safety Extra Low Voltage). Typical voltage in an Ethernet application is 48-volt power. Power converter 238 may then further transform the power as a DC to DC converter to provide 1.8 to 3.3 volts, or other voltages specified by many Ethernet network attached devices.

Power-sourcing switch 270 includes a network connector 232, Ethernet or network physical layer 254, PSE controller 256, non-magnetic transformer and choke power supply circuitry 266, and possibly a multiple-port switch. Transformer functionality is supplied by non-magnetic transformer and choke power supply circuitry 266. Power-sourcing switch 270 may be used to supply power to network attached devices. Powered end station 272 and power sourcing switch 270 may be applied to an Ethernet application or other network-based applications such as, but not limited to, a vehicle-based network such as those found in an automobile, aircraft, mass transit system, or other like vehicle. Examples of specific vehicle-based networks may include a local interconnect network (LIN), a controller area network (CAN), or a flex ray network. All may be applied specifically to automotive networks for the distribution of power and data within the automobile to various monitoring circuits or for the distribution and powering of entertainment devices, such as entertainment systems, video and audio entertainment systems often found in today's vehicles. Other networks may include a high speed data network, low speed data network, time-triggered communication on CAN (TTCAN) network, a J1939-compliant network, ISO 1898-compliant network, an ISO 11519-2-compliant network, as well as other similar networks. Other embodiments may supply power to network attached devices over alternative networks such as but not limited to a HomePNA local area network and other similar networks. HomePNA uses existing telephone wires to share a single network connection within a home or building. Alternatively, embodiments may be applied where network data signals are provided over power lines.

Non-magnetic transformer and choke power feed circuitry 262 and 266 enable elimination of magnetic transformers with integrated system solutions that enable an increase in system density by replacing magnetic transformers with solid state power feed circuitry in the form of an integrated circuit or discreet component.

In some embodiments, non-magnetic transformer and choke power feed circuitry 262, network physical layer 236, power distribution management circuitry 254, and power converter 238 may be integrated into a single integrated circuit rather than discrete components at the printed circuit board level. Optional protection and power conditioning circuitry may be used to interface the integrated circuit to the network connector 232.

The Ethernet PHY may support the 10/100/1000 Mbps data rate and other future data networks such as a 10000 Mbps Ethernet network. Non-magnetic transformer and choke power feed circuitry 262 supplies line power minus the insertion loss directly to power converter 238, converting power first to a 12V supply then subsequently to lower supply levels. The circuit may be implemented in any appropriate process, for example a 0.18 or 0.13 micron process or any suitable size process.

Non-magnetic transformer and choke power feed circuitry 262 may implement functions including IEEE 802.3.af signaling and load compliance, local unregulated supply generation with surge current protection, and signal transfer between the line and integrated Ethernet PHY. Since devices are directly connected to the line, the circuit may be implemented to withstand a secondary lightning surge.

For the power over Ethernet (PoE) to be IEEE 802.3af standard compliant, the PoE may be configured to accept power with various power feeding schemes and handle power polarity reversal. A rectifier, such as a diode bridge, a switching network, or other circuit, may be implemented to ensure power signals having an appropriate polarity are delivered to nodes of the power feed circuit. Any one of the conductors 1, 4, 7 or 3 of the network RJ45 connection can forward bias to deliver current and any one of the return diodes connected can forward bias to form a return current path via one of the remaining conductors. Conductors 2, 5, 8 and 4 are connected similarly.

Non-magnetic transformer and choke power feed circuitry 262 applied to PSE may take the form of a single or multiple port switch to supply power to single or multiple devices attached to the network. Power sourcing switch 270 may be operable to receive power and data signals and combine to communicate power signals which are then distributed via an attached network. If power sourcing switch 270 is a gateway or router, a high-speed uplink couples to a network such as an Ethernet network or other network. The data signal is relayed via network PHY 254 and supplied to non-magnetic transformer and choke power feed circuitry 266. PSE switch 270 may be attached to an AC power supply or other internal or external power supply to supply a power signal to be distributed to network-attached devices that couple to power sourcing switch 270. Power controller 256 within or coupled to non-magnetic transformer and choke power feed circuitry 266 may determine, in accordance with IEEE standard 802.3af, whether a network-attached device in the case of an Ethernet network-attached device is a device operable to receive power from power supply equipment. When determined that an IEEE 802.3af compliant powered device (PD) is attached to the network, power controller 256 may supply power from power supply to non-magnetic transformer and choke power feed circuitry 266, which is sent to the downstream network-attached device through network connectors, which in the case of the Ethernet network may be an RJ45 receptacle and cable.

IEEE 802.3af Standard is to fully comply with existing non-line powered Ethernet network systems. Accordingly, PSE detects via a well-defined procedure whether the far end is PoE compliant and classify sufficient power prior to applying power to the system. Maximum allowed voltage is 57 volts for compliance with SELV (Safety Extra Low Voltage) limits.

For backward compatibility with non-powered systems, applied DC voltage begins at a very low voltage and only begins to deliver power after confirmation that a PoE device is present. In the classification phase, the PSE applies a voltage between 14.5V and 20.5V, measures the current and determines the power class of the device. In one embodiment the current signature is applied for voltages above 12.5V and below 23 Volts. Current signature range is 0-44 mA.

The normal powering mode is switched on when the PSE voltage crosses 42 Volts where power MOSFETs are enabled and the large bypass capacitor begins to charge.

A maintain power signature is applied in the PoE signature block—a minimum of 10 mA and a maximum of 23.5 kohms may be applied for the PSE to continue to feed power. The maximum current allowed is limited by the power class of the device (class 0-3 are defined). For class 0, 12.95W is the maximum power dissipation allowed and 400 ma is the maximum peak current. Once activated, the PoE will shut down if the applied voltage falls below 30V and disconnect the power MOSFETs from the line.

Power feed devices in normal power mode provide a differential open circuit at the Ethernet signal frequencies and a differential short at lower frequencies. The common mode circuit presents the capacitive and power management load at frequencies determined by the gate control circuit.

Terms “substantially”, “essentially”, or “approximately”, that may be used herein, relate to an industry-accepted tolerance to the corresponding term. Such an industry-accepted tolerance ranges from less than one percent to twenty percent and corresponds to, but is not limited to, component values, integrated circuit process variations, temperature variations, rise and fall times, and/or thermal noise. The term “coupled”, as may be used herein, includes direct coupling and indirect coupling via another component, element, circuit, or module where, for indirect coupling, the intervening component, element, circuit, or module does not modify the information of a signal but may adjust its current level, voltage level, and/or power level. Inferred coupling, for example where one element is coupled to another element by inference, includes direct and indirect coupling between two elements in the same manner as “coupled”.

While the present disclosure describes various embodiments, these embodiments are to be understood as illustrative and do not limit the claim scope. Many variations, modifications, additions and improvements of the described embodiments are possible. For example, those having ordinary skill in the art will readily implement the steps necessary to provide the structures and methods disclosed herein, and will understand that the process parameters, materials, and dimensions are given by way of example only. The parameters, materials, and dimensions can be varied to achieve the desired structure as well as modifications, which are within the scope of the claims. Variations and modifications of the embodiments disclosed herein may also be made while remaining within the scope of the following claims. For example, various aspects or portions of a network interface are described including several optional implementations for particular portions. Any suitable combination or permutation of the disclosed designs may be implemented. 

1. A power converter comprising: an input connection to a single power source; an output connection to a single coil; a daisy-chain connection coupled to the output connection and configured to enable coupling of at least one additional daisy-chained power converter and at least one respective additional power source to the single coil; a power integrator coupled between the input connection and the output connection and adapted for summing power from the power sources into a single voltage on the single coil; and a time multiplexer coupled to the power integrator configured to control power integration.
 2. The power converter according to claim 1 further comprising: the power integrator comprising a pulse width modulation circuit; the time multiplexer comprising an oscillator, a divide-by-N circuit coupled to the oscillator whereby N corresponds to the number of daisy-chained power converters, a detect clock configured to detect a clock signal from a daisy-chained power converter, and a multiplexer coupled to receive input signals from the divide-by-N circuit and the detect clock and coupled to drive the pulse width modulation circuit; the single coil comprising a primary winding of a single flyback transformer; and at least one optical isolator configured to isolate a secondary winding of the single flyback transformer.
 3. The power converter according to claim 1 further comprising: the power integrator comprising a pulse width modulation circuit; the time multiplexer comprising an oscillator, a divide-by-N circuit coupled to the oscillator whereby N corresponds to the number of daisy-chained power converters, a detect clock configured to detect a clock signal from a daisy-chained power converter, and a multiplexer coupled to receive input signals from the divide-by-N circuit and the detect clock and coupled to drive the pulse width modulation circuit; and the single coil comprising a buck inductor.
 4. The power converter according to claim 1 further comprising: the power integrator comprising a pulse width modulation circuit; the time multiplexer comprising a delay-locked loop coupled to drive the pulse width modulation circuit, an oscillator, a detect clock configured to detect a clock signal from a daisy-chained power converter, a multiplexer coupled to receive input signals from the oscillator and the detect clock and coupled to drive the delay-locked loop; the single coil comprising a primary winding of a single flyback transformer; and at least one optical isolator configured to isolate a secondary winding of the single flyback transformer.
 5. The power converter according to claim 1 further comprising: the power integrator comprising a pulse width modulation circuit; the time multiplexer comprising a delay-locked loop coupled to drive the pulse width modulation circuit, an oscillator, a detect clock configured to detect a clock signal from a daisy-chained power converter, a multiplexer coupled to receive input signals from the oscillator and the detect clock and coupled to drive the delay-locked loop; and the single coil comprising a buck inductor.
 6. The power converter according to claim 1 further comprising: the power converter configured as a Power-over-Ethernet (PoE) integrated circuit; the single power source configured as two wire pairs coupled to a Registered Jack (RJ)-45 connector; a magnetic transformer coupled to the RJ-45 connector; a Powered Device (PD) controller coupled to the single power source; a diode bridge coupling the single power source to the PD controller; and a Powered Device (PD) coupled to the single coil, powered by the single voltage.
 7. The power converter according to claim 1 further comprising: the power converter configured as a Power-over-Ethernet (PoE) integrated circuit; the single power source configured as two wire pairs coupled to a Registered Jack (RJ)-45 connector; a non-magnetic transformer and diode bridge integrated into the PoE integrated circuit and coupled to the RJ-45 connector; a Powered Device (PD) controller coupled to the single power source; a diode bridge coupling the single power source to the PD controller; and a Powered Device (PD) coupled to the single coil, powered by the single voltage.
 8. The power converter according to claim 1 further comprising: the time multiplexer configured to perform adaptive power sharing for the power integrator based on power availability of the single power source and the additional power sources.
 9. The power converter according to claim 1 further comprising: a current sensor coupled to the power integrator; and the time multiplexer configured to detect a current sensed by the current sensor that exceeds a predetermined maximum current and, in response to the current exceeding the maximum current, switching sourcing to one of the additional power sources.
 10. The power converter according to claim 9 further comprising: the time multiplexer configured to adaptively change the predetermined maximum current whereby power sourced by the single power source and the additional power sources is adaptively managed.
 11. The power converter according to claim 1 further comprising: the single power source and the additional power sources are selected from among two-wire pair sources and auxiliary sources.
 12. The power converter according to claim 1 further comprising: a Powered Device (PD) coupled to the single coil, powered by the single voltage; the input connection coupled to a Power Sourcing Equipment (PSE); and a controller configured to communicate detection, classification, and operational information between the Power Sourcing Equipment (PSE) and the Powered Device (PD) for accommodating a power consumption classification of the PD and identifying characteristics of the single power source and/or the additional power sources for sharing power adaptively by the time multiplexer.
 13. The power converter according to claim 12 further comprising: the controller configured to communicate detection, classification, and operational information independently for each power source of the single power source and the additional power sources and for current power consumption demand of the Powered Device (PD) for identifying characteristics of the power sources.
 14. The power converter according to claim 1 further comprising: the power converter operative in a single integrated circuit chip configuration whereby the single power source supplies the output connection to the single coil; and the power converter operative in combination with a plurality of single integrated circuit chip in a daisy chain configuration as additional power sources become available, whereby time multiplexers for the plurality of power converters schedule power source control with the output connections coupled in parallel to the single coil.
 15. A Power-over-Ethernet (PoE) system comprising: at least one modular power converter configured for coupling between a respective at least one power source and a single coil of a Powered Device (PD) in a daisy-chain arrangement whereby output connections of the at least one modular power converter are coupled in parallel to the single coil, the individual modular power converters comprising a power integrator and a time multiplexed scheduler coupled to the power integrator and configured to drive multiple power integrators for multiple modular power converters to integrate power from corresponding multiple sources into a single voltage on the single coil.
 16. The system according to claim 15 wherein the at least one modular power converter further comprises: the power converter configured as a Power-over-Ethernet (PoE) integrated circuit; a single power source configured as two wire pairs coupled to a Registered Jack (RJ)-45 connector; a magnetic transformer coupled to the RJ-45 connector; a Powered Device (PD) controller coupled to the single power source; and a diode bridge coupling the single power source to the PD controller.
 17. The system according to claim 15 wherein the at least one modular power converter further comprises: the power converter configured as a Power-over-Ethernet (PoE) integrated circuit; the single power source configured as two wire pairs coupled to a Registered Jack (RJ)-45 connector; a non-magnetic transformer and diode bridge integrated into the PoE integrated circuit and coupled to the RJ-45 connectors; a Powered Device (PD) controller coupled to the single power source; and a diode bridge coupling the single power source to the PD controller.
 18. The system according to claim 15 further comprising: the time multiplexed scheduler configured to perform adaptive power sharing for the power integrator based on power availability of the at least one power source.
 19. The system according to claim 15 wherein the at least one modular power converter further comprises: a current sensor coupled to the power integrator; and the time multiplexed scheduler configured to detect a current sensed by the current sensor that exceeds a predetermined maximum current and, in response to the current exceeding the maximum current, switching sourcing of the at least one power source.
 20. The system according to claim 19 further comprising: the time multiplexed scheduler configured to adaptively change the predetermined maximum current whereby power sourced by the at least one power source is adaptively managed.
 21. The system according to claim 15 further comprising: the at least one power source is selected from among two-wire pair sources and auxiliary sources.
 22. The power converter according to claim 15 further comprising: a Powered Device (PD) coupled to the single coil, powered by the single voltage; the at least one power source comprising at least one Power Sourcing Equipment (PSE); and a controller configured to communicate detection, classification, and operational information between the at least one Power Sourcing Equipment (PSE) and the Powered Device (PD) for accommodating a power consumption classification of the PD and identifying characteristics of the at least one power source for sharing power adaptively by the time multiplexed scheduler.
 23. The power converter according to claim 22 further comprising: the controller configured to communicate detection, classification, and operational information independently for each power source of the single power source and the additional power sources and for current power consumption demand of the Powered Device (PD) for identifying characteristics of the power sources.
 24. The system according to claim 15 further comprising: the individual modular power converters operative in a single integrated circuit chip configuration whereby a single power source supplies the output connection to the single coil; and a plurality of the modular power converters operative in combination in a daisy chain configuration as additional power sources become available, whereby time multiplexed schedulers for the plurality of modular power converters schedule power source control with the output connections coupled in parallel to the single coil.
 25. A system according to claim 15 further comprising: the single coil is selected from a primary winding of a single flyback transformer or a buck inductor; the power integrator is selected from a group consisting of a Pulse Width Modulator (PWM), a forward bridge, a half bridge, a Pulse Frequency Modulator (PFM), and a Pulse Amplitude Modulator (PAM); and a time multiplexed scheduler control element selected from a group consisting of a divide-by-N circuit and a Delay-Locked Loop (DLL).
 26. A method for power conversion in a network device comprising: integrating power from a plurality of sources into a single voltage; driving power integration according to time multiplexed scheduling; and applying the integrated power onto a single winding of a flyback transformer or buck inductor.
 27. The method according to claim 26 further comprising: converting power in a Power-over-Ethernet (PoE) configuration; and integrating power from at least two sources selected from two-wire pair sources and auxiliary sources.
 28. The method according to claim 26 further comprising: determining power available among the plurality of sources; and adaptively sharing power based on the determined power availability.
 29. The method according to claim 26 further comprising: measuring current associated with the power sources; determining when the measured current exceeds a predetermined current limit; and adaptively switching power sourcing when the current limit is exceeded.
 30. The method according to claim 27 further comprising: adaptively changing current limits for the power source plurality; and adaptively managing power sourced among the power source plurality. 